<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="app">
   <input type="text" v-model="add" @keyup.enter="fn($event,1)"/>
    <ul>
        <li v-for="a in arr">{{a}}</li>
    </ul>

</div>

</body>
<script src="../node_modules/vue/dist/vue.js"></script>
<script>
   let vm =  new Vue({
        el: '#app',
       data:{
            add:'',
           arr:[]
       },
        methods:{
            fn(e){

                    this.arr.push(this.add);
                    this.add='';

            }
        }
    })


</script>
</html>